Transport for London has already been using biofuel from waste products such as cooking oil in London's 9,500 buses, but this is thought to be the first time a coffee-based biofuel has been added to London's transport system.

And it's not like there isn't enough coffee waste to go around as the British Coffee Association says a whopping 55 million cups of coffee are drunk every day in the UK.

Londoners alone create 200,000 tonnes of coffee waste every year, according to bio-bean who take the used coffee grounds from cafes and instant coffee factories and extract oil from it.